As one of typical methods of manufacturing a glass ribbon, there is widely known an overflow downd-raw process for causing molten glass to flow down from a compact to form a glass ribbon.
A glass ribbon manufacturing apparatus using the overflow downd-raw process generally has a forming region in which the molten glass is caused to flow down from the compact to form a glass ribbon having a predetermined width dimension, an annealing region in which the formed glass ribbon is annealed to remove an internal strain thereof, and a cooling region in which the annealed glass ribbon is cooled to the vicinity of a room temperature. Further, it is general to provide a plurality of rollers configured to support both sides of the glass ribbon in a width direction along the glass ribbon.
The glass ribbon immediately after the formation in the forming region is in a state in which the glass ribbon is not completely hardened yet. A shape thereof is fixed along with the annealing in the annealing region. At this time, the glass ribbon sometimes exhibits a tendency to be curved in the width direction in an annealing process. It is difficult to stabilize the above-mentioned curved shape of the glass ribbon, in particular, a direction of curvature with convexity to a front side or a rear side by existing equipment. Due to the difficulty, there is a fear in that quality of the manufactured glass ribbon, and eventually, quality of a glass sheet may be varied.
To cope with the above-mentioned problem, for example, in the invention disclosed in Patent Literature 1, the shape of the glass ribbon is stabilized by arranging rollers configured to nip the both sides of the currently moved down glass ribbon in the width direction in a state in which axes thereof are inclined within a horizontal plane so as to extend along a curved shape of the glass ribbon.